Emergency declared in US town after shooting

A state of emergency was declared in a Missouri county as protesters turned violent after police shot and critically injured one man Sunday, the anniversary of the killing of an unarmed black teenager Michael Brown

"The recent acts of violence will not be tolerated in a community that has worked so tirelessly over the last year to rebuild and become stronger," St. Louis County Executive Steve Stenger said in a statement Monday.

Overnight unrest in Ferguson, a small town of 22,000, nearly 70 percent of them black, with all but four of its 53 strong police force white, created "the potential for harm to persons and property," the statement said.

The order came as roughly 200 demonstrators marched from Christ Church Cathedral to the Thomas F. Eagleton United States Courthouse in St. Louis.

The protesters carried signs, chanted and prayed and demanded the Justice Department take action, according to CNN affiliate KTVI.

At the Old Courthouse in downtown St. Louis, protesters hung a banner from two balloons. It read, "Racism still lives here #fightback."

Police arrested 56 people at the courthouse demonstration, St. Louis Metropolitan Police Department spokesperson Schron Jackson told CNN.

Later Monday, another group of protesters blocked part of a highway in Earth City, Missouri. Some of them held yellow signs that said, "Ferguson is everywhere."

Monday's planned acts of civil disobedience came after a night of violence that left Ferguson on edge.

Peaceful marches in the St. Louis suburb planned by day on Sunday were shattered that same night when gunfire broke out, sending protesters and police scattering to safety.

The alleged gunman, 18-year-old Tyrone Harris of St. Louis, is hospitalised in critical condition and in police custody.

Harris' aunt, Karen Harris, said her nephew attended the protests because he was friends with Brown.

Recounting what other family members who were with Tyrone Harris described, the aunt said Tyrone Harris wasn't carrying a gun and never fired at police.

He was "running for his life" just like everyone else, she said, when the gunshots were fired.

Brown's killing on Aug 9, 2014 by White police Officer Darren Wilson sparked outrage and protests nationwide against what some described as racial bias by the police.